As a technique of preventing authentication information from being peeped at the time of input, the viewing angle of the display screen is narrowed or alternatively inputted numeric characters are displayed with “*” marks or the like so that the number of inputted digits is solely shown.
Further, as a PIN number input device in which a user inputs a PIN number by using ten keys in a terminal of an automated teller machine (ATM) or the like, such a device is known in which an input ten-key screen and a fake input ten-key screen are displayed and then dummy digits are inserted into the PIN number so that even when the movement of the inputting hand is seen, the PIN number is prevented from being stolen (for example, see Patent Document 1).